Study On The Counter Electrode For Dye-sensituzed Solar Cell

Dye-sensitized solar cells(DSSCs)had attracted much attention due to its low-cost,high efficiency and easy fabrication.This paper carried out three parts which were based on the starting point of improving the photo-electric conversion efficiency and performance of DSSCs.The first part was to prepare high performance Pt counter electrode by improving the distrubution of Pt particles on the film;the second part studied the effects of firing temperature on the performance of active carbon,TiC and carbon black counter electrode;the third part improved the adhesion strength of carbon and carbides counter electrodes by using the polymer solution prepared by polymer-solution phase seperation technic.SEM was used to characterize each film and XRD was used to characterize active carbon,TiC and carbon black.The I-V curves,CV,EIS and tafel measurement of each counter electrode film were tested.The specific studies and results were as follow:(1)Three kinds of excellent thermal deposition Pt counter electrodes were prepared by vacuum-assisted titration method,capillary force method and screen printing method.By control the titration amount and printing times to control the loading amount of Pt.When the amount was 0.45ml,the vacuum-assisted titration thermal deposition Pt DSSC was optimum,showing an efficiency of 7.20%,and the open-circuit voltage(Voc),short-circuit current(Jsc),fill factor(FF)and charge transfer resistance(Rct)were 0.73V,13.79 mA·cm-2,0.71,7.20%and 1.52 respectively.And the Pt particles distributed uniformly forming a continuous Pt film which avoided the deficiency of bad distribution of traditional thermal deposition method.When the titration times of the capillary force method were 7 times,the Voc,Jsc,FF,efficiency and Rct were 0.69V,11.13 mA·cm-2,0.69,5.30%and 3.80?,respectively.When the printing times of the screen printing method were 2 times,the the Voc,Jsc,FF,efficiency and Rct were 0.75V,13.03 mA·cm-2,0.69,6.77%and 2.17 ?,respectively.And the Pt particles distributed uniformly forming a continuous Pt film and no aggregation appeared which avoided the deficiency of the thermal deposition method.(2)The effects of firing temperature on the performance of the counter electrodes prepared by active cabon,TiC and carbon black were studied.The performance of active carbon and TiC counter elctrodes improved as the firing temperature improved.When firing temperature was 500?,the active cabon and TiC DSSC attained optimum efficiencies,which were 4.58%and 6.85%,respectively.With the firing temperature increasing,the performance of carbon black elctrode decreased.When the firing temperature were 400?,the efficiency was 6.95%.(3)Polymer solution was prepared by polymer-solution phase separation technic.At room temperature its viscosity could be controled and it was easily mixed with powder material,and at high temperature it could split into carbon.The adhesion strength of the three kinds of counter electrodes prepared by the polymer soluntion and active carbon,TiC and carbon black improved significantly.PEG600(PEG),30%PEG-70%polymer solution,70%PEG-30%polymer solution and polymer solution were each used as binder to prepare counter electrodes with active carbon,TiC and carbon black,respectively.The bonding strength of the three series counter electrodes preprared by the above four binders was tested by 3M scotch tape.The results showed that the adhesion strength improved with the proportion of polymer solution in the binder increased.(4)Avtive carbon counter electrode prepared by using 70%PEG-30%polymer solution as binder reached an efficiency of 6.19%,which was much higher than that of the electrode prepared by using PEG as binder.The Voc,Jsc,FF and Rct were 0.78V,13.08 mA·cm-2,0.60 and 2.28?,respectively.The adhesion strength also improved significantly.Although the efficiencies of TiC and carbon black electrodes prepared by using 70%PEG-30%polymer solution as binder was slightly lower than that prepared by using PEG as binder,the adhesion strength improved significantly.The Voc,Jsc,FF,efficiency and Rct of the DSSC assembled by TiC counter electrodes prepared by using 70%polymer solution-30%PEG as binder were 0.71V,14.09 mA·cm-2,0.57,5.74%and 2.13 respectively;The Voc,Jsc,FF,efficiency and Rct of the DSSC assembled by carbon black counter electrodes prepared by using 70%polymer solution-30%PEG as binder were 0.72V,13.65 mA·cm-2,0.64,6.29%and 3.96 ?,respectively.